Emerging research suggests that grapes, as part of a healthy diet and lifestyle, may contribute to health.  The studies below look at the variety of ways in which grapes may play a role in maintaining certain aspects of health that can decline as we age.

The promising study results provided here will contribute to future research in these areas.

In most all of the studies cited below, the researchers used a whole grape powder made from whole fresh grapes – a mix of red, green, and black varieties – that were ground and freeze-dried.  Using the grape powder allows for year-round study of grapes by researchers.  The whole grape powder is a substitute for fresh grapes.

A grape-enriched diet protected against metabolic brain decline in Alzheimer’s-related areas of the brain.¹

In a pilot study of people with early memory decline, subjects were either fed whole grape powder equivalent to just 2 ¼ cups of grapes per day – or a placebo powder.  The results showed that consuming grapes preserved healthy metabolic activity in regions of the brain associated with early Alzheimer’s disease, where metabolic decline takes hold.  Subjects who didn’t consume grapes exhibited significant metabolic decline in these critical regions.  Additionally, those consuming the grape-enriched diet showed beneficial changes in regional brain metabolism that correlated to improvements in attention and working memory performance.

 

Grape consumption altered gene expression in the brain and had positive effects on behavior and cognition.²

In this study, researchers looked at gene expression in groups of mice that had been on either a standard diet, a high-fat diet, or a high-fat diet with grapes added and found within each group unique alterations of gene expression. Grape supplementation altered gene expression in a way that mapped more closely with the standard diet, suggesting the ability to mitigate the negative effects of a high-fat diet. Specifically, the grape-enriched diet resulted in beneficial effects on anxiety-like behavior and feeding behavior that contributes to better cognition and memory in mice that were exposed to a high-fat diet for a long duration.

 

Grape consumption helped protect brain neurons from oxidative damage and cell death, and decreased inflammation.³

In this study, animals were fed a control diet or a grape-enriched diet at one of two levels:  low and high amounts of grapes.  Both grape diets helped protect against neuronal damage caused by loss of oxygen in the brain.  Animals not receiving a grape-enriched diet had extensive damage.  Grapes also reduced inflammation in the support cells to the neurons.

 

A grape-supplemented diet helped protect against oxidative stress-induced anxiety, memory impairment, and associated high blood pressure.^4,5

This animal study investigated the role of oxidative stress in the combined occurrence of anxiety, cognitive impairment, and hypertension, using a model of oxidative stress.  The grape-fed animals exhibited a reduction in anxiety-like behavior, and no increase in blood pressure or memory impairment, which the researchers attributed to the antioxidant capacity/activity of the grape polyphenols.

A second, and similar study by the same research team, investigated the role of diminished estrogen influence at menopause and its association with oxidative stress and resulting cognitive decline, heightened anxiety, and hypertension.  The control animals had increased blood pressure, anxiety-like behavior, and learning memory impairment.  They exhibited increased oxidative stress in the brain, serum, and urine, and lower amounts of an antioxidant enzyme in the brain.  Those consuming the grape-enriched diet reversed these effects.

 

Adding grapes to the diet helped protect against cognitive, behavioral, and biochemical impairments related to traumatic stress.⁶

A third study looked at the effects of a grape-enriched diet on post-traumatic stress in animals.  In this study, the animals consuming grape powder reversed the behavioral and memory problems that were observed in those not receiving a grape-enriched diet.  The researchers attributed these benefits to both gene activation and enhanced antioxidant activity resulting from grape intake.

 

1. Lee, J.K., Torosyan, N., & Silverman, D.H. (2017).  Examining the impact of grape consumption on brain metabolism and cognitive function in patients with mild decline in cognition: A double-blinded placebo controlled pilot study. Experimental Gerontology, 87 (Pt A), 121-128. doi.org/10.1016/j.exger.2016.10.004 

2. Parande, F.; Dave, A.; Park, E.-J.; McAllister, C.; Pezzuto, J.M. (2022). Effect of Dietary Grapes on Female C57BL6/J Mice consuming a high-fat diet: behavioral and genetic changes. Antioxidants, 11, 414. doi.org/10.3390/antiox11020414 

3. Wang, Q., Simonyi, A., Li, W., Sisk, B.A., Miller, R.L., MacDonald, R.S., …Sun, A.Y. (2005).  Dietary grape supplement ameliorates cerebral ischemia-induced neuronal death in gerbils. Molecular Nutrition and Food Research, 49, 443-451. doi.org/10.1002/mnfr.200500019 

4. Allam F., Dao, A.T., Ghugh, G., Bohat, R., Jafri, F., Patki, G., …Salim, S. (2013, June).  Grape powder supplementation prevents oxidative stress-induced anxiety-like behavior, memory impairment, and high blood pressure in rats.  Journal of Nutrition, 143(6), 835-842. doi.org/10.3945/jn.113.174649

5. Patki, G., Allam, F.H., Atrooz, F., Dao, A.T., Solanki, N., Chugh, G., … Salim, S. (2013, September).  Grape powder intake prevents ovariectomy-induced anxiety-like behavior, memory impairment and high blood pressure in female Wistar rats.  PLoS ONE, 8(9), e74522. doi.org/10.1371/journal.pone.0074522

6. Solanki, N., Alkadhi, I., Atrooz, F., Patki, G., & Salim, S. (2015, January).  Grape powder prevents cognitive, behavioral and biochemical impairments in a rat model of post-traumatic stress disorder.  Journal of Nutrition Research, 35(1), 65-75. doi.org/10.1016/j.nutres.2014.11.008

A grape-enriched diet reduced the expression of cancer-promoting genes in healthy colon tissue. ^{7, 8}

In a human study of five colon cancer patients, researchers studied the effects of consuming grapes on colon tissue.  The subjects consumed whole grape powder every day for two weeks; samples of healthy and cancerous colon tissues were taken before and after consuming the grape diet.  The results showed that subjects consuming the equivalent of 2 1/2 cups of grapes for two weeks showed a 47% reduction in the expression of certain target genes involved in the WNT-signaling pathway that are responsible for promoting tumor growth in the colon.  This beneficial effect was seen in the subjects’ healthy colon tissue, but not the cancerous, suggesting that regular consumption of grapes may help to maintain a healthy colon.

In a second study, 30 healthy subjects were randomly assigned to one of three diets: consuming either 1/3, 2/3, or one pound of grapes each day for two weeks.  Samples of colon tissue were taken before and after consuming the grape diets. The results showed that grape consumption at all three levels inhibited the expression of Wnt pathway target genes and markers of mucosal proliferation involved in cancer promotion.  The researchers noted that the potential benefits of grape intake are most significant for high-risk older individuals and individuals whose diet is high in arginine intake; both of these groups have an increased incidence of colon cancer.

Grape consumption helped increase diversity of gut microbiome.⁹

In this human study, healthy subjects consumed grape powder equal to 1.5 cups of grapes per day, for four weeks. After four weeks of grape consumption, there was an increase in microbial diversity as measured by the Shannon index.

Consuming grapes helped counter the adverse effects of a high saturated fat diet and promote improvements in gut bacteria and intestinal health.^{10, 11} 

In one study, animals consuming a high saturated fat diet that was supplemented with grapes (3% or 5% of the diet) exhibited reductions in overall and subcutaneous body fat that were positively associated with beneficial changes in intestinal bacteria and health; e.g., increases in some beneficial bacteria, decreases in some less desirable bacteria, increased microbial diversity, and improved gut barrier function.

In a second study, consuming grape polyphenols in addition to a high-fat diet reduced the percentage of body fat, including subcutaneous and visceral fat deposits; reduced markers of inflammation; improved glucose tolerance and intestinal barrier function.

 

7. Nguyen, A.V., Marinez, M., Stamos, M.J., Moyer, M.P., Planutis, K., Hope, C., & Holcombe, R.F. (2009). Results of a phase I clinical trial examining the effect of plant-derived resveratrol and grape powder on Wnt pathway target gene expression in colonic mucosa and colon cancer. Journal of Cancer Management and Research, 1, 25-37. www.ncbi.nlm.nih.gov/pmc/articles/pmc3004662/ 

8. Holcombe, R.F., Martinez, M., Planutis, K., & Planutiene, M. (2015). Effects of a grape-supplemented diet on proliferation and Wnt signaling in the colonic mucosa are greatest for those over 50 and with high arginine consumption.  Nutrition Journal, 14:62. doi.org/10.1186/s12937-015-0050-z

9. Yang, J.; Kurnia, P.; Henning, S.M.; Lee, R.; Huang, J.; Garcia, M.C.; Surampudi, V.; Heber, D.; Li, Z. (2021). Effect of standardized grape powder consumption on the gut microbiome of healthy subjects: a pilot study. Nutrients, 13, 3965. doi.org/10.3390/nu13113965

10. Baldwin, J., Collins, B., Wolf, P.G., Martinez, K., Shen, W., Chuang, C.C., …McIntosh, M.K. (2016).  Table grape consumption reduces adiposity and markers of hepatic lipogenesis and alters gut microbiota in butter fat-fed mice. Journal of Nutritional Biochemistry, 27, 123-135. doi.org/10.1016/j.jnutbio.2015.08.027 

11. Collins, B., Hoffman, J., Martinez, K., Grace, M., Lila, M.A., Cockrell, C., …McIntosh, M.K. (2016).  A polyphenol-rich fraction obtained from table grapes decreases adiposity, insulin resistance and markers of inflammation and impacts gut microbiota in high-fat-fed mice. Journal of Nutritional Biochemistry, 31, 150-165. doi.org/10.1016/j.jnutbio.2015.12.021 

Grape intake improved macular pigment accumulation and key biomarkers of eye health.¹²

In this human study, consuming grapes for four months weeks improved key markers of eye health in older adults, including macular pigment accumulation. For 16 weeks human subjects consumed either grapes (equivalent to 1 ½ cups of grapes per day) or a placebo. The grape eaters showed a significant increase in macular pigment optical density (MPOD), an indicator of healthy eyes; plus increased plasma antioxidant capacity and total phenolic content compared to those on placebo. Those who didn’t consume grapes saw a significant increase in harmful advanced glycation end products (AGEs), which can damage vascular components of the retina, impair cellular function, and cause oxidative stress.

Grape consumption protected against UV light-induced cataracts.¹³

In this study, for 3 months mice either consumed a 5%, 10% or 15% grape-enriched diet – designed to mimic one, two, or three servings of grapes per day in humans – or a diet with no grapes. Researchers identified a dose dependent protective response, where the 15% diet nearly abolished any sign of cataracts. The protective effects of grapes were attributed to their antioxidant capacity and ability to 1) improve the balance in the redox state (oxidative and antioxidant signaling); 2) mitigate UV stress response pathways; and 3) to activate the XIAP pathway of a key protein that protects against cell death.

Regular consumption of a grape-enriched diet helped protect the retina from damage in three laboratory models of age-related macular degeneration. ^{14, 15, 16}

In the first study, adding grapes to the diet early in life prevented blindness in animals prone to developing retinal damage in old age. The grape-enriched diet protected against oxidative damage to the retina by protecting the function of its retinal epithelium pigment cells. This study showed that consuming grapes at an early age protected vision into old age.

In another animal model of macular degeneration, a grape-enriched diet preserved retinal function in multiple ways, from countering oxidative stress, to lowering inflammatory proteins, and increasing protective proteins in the retina.

In a third study, supplementing the diet with grapes helped reduce damaging and undesirable blood vessel formation in the choroid layer of the eye that can leak into the retina and lead to vision loss.

 

12. Hu, W., Zheng, R., Feng, Y., Tan, D., Chung-Tsing, G.C., Su, X., and Kim, J.E. (2023). Impacts of regular consumption of grapes on macular pigment accumulation in Singapore older adults: a randomized, controlled trial. Food Funct. 14, 8321-8330. doi.org/10.1039/d3fo02105j

13. Liu, X., Yu, Y., Garcia, L.A., Au, M.L., Tran, M., Zhang, J., Lou, A., Liu, Y., & Wu, H. (2024). A grape-supplemented diet prevented ultraviolet (UV) radiation-induced cataract by regulating Nrf2 and XIAP pathways. The Journal of Nutritional Biochemistry, doi.org/10.1016/j.jnutbio.2024.109636

14. Yu, C.C., Nandrot, E.F., Dun, Y., & Finnemann, S.C. (2012).  Dietary antioxidants prevent age-related retinal pigment epithelium actin damage and blindness in mice lacking ?v?5 integrin. Free Radical Biology and Medicine, 52(3), 660-70. doi.org/10.1016/j.freeradbiomed.2011.11.021

15. Patel, A.K., Davis, A., Rodriguez, M.E., Agron, S., & Hackam, A.S. (2016).  Protective effects of a grape-supplemented diet in a mouse model of retinal degeneration. Nutrition, 32: 384-390. doi.org/10.1016/j.nut.2015.09.017 

16. Kanavi, M.R., Darjatmoko, S., Wang, S., Azari, A.A., Farnoodian, M., Kenealey, J.D., …Polans, A.S. (2014).  The sustained delivery of resveratrol or a defined grape powder inhibits new blood vessel formation in a mouse model of choroidal neovascularization. Molecules, 19, 17578-17603. doi.org/10.3390/molecules191117578 

Consuming grapes helped protect against UV damage to skin.^{17, 18, 19}

In a human pilot study, subjects consuming grapes (equivalent to 2.25 cups per day) showed increased resistance to sunburn and a reduction in markers of UV damage at the cellular level. Subjects’ skin response to UV light was measured before and after consuming grapes by determining the Minimal Erythema Dose (MED). Grape consumption was protective; more UV exposure was required to cause sunburn following grape consumption, with MED increasing on average by 74.8%. Analysis of skin biopsies showed that the grape diet was associated with decreased DNA damage, fewer deaths of skin cells, and a reduction in inflammatory markers.

In a second study, 29 human volunteers consumed whole grape powder – equivalent to 2.25 cups of grapes per day – for 14 days. Measurement of MED plus metabolomic analysis of the gut microbiome, blood, and urinary samples was undertaken. One-third of the subjects showed increased UV resistance following grape consumption, and these same subjects displayed significant differences in the microbiome and metabolome, compared to non-responders.

A grape-enriched diet helped protect against UVB radiation-mediated skin cancer.^{20, 21, 22}

In a study using an animal model for UVB-induced skin cancer, consuming either a 3% or 5% grape powder diet for 28 weeks significantly inhibited tumor incidence and delayed the onset of tumor growth.  The grape-mediated protective response was accompanied by enhanced DNA damage repair; reduced proliferation; increased cancer cell death; and beneficial changes in several markers of oxidative stress.

In evaluating the potential mechanisms for the beneficial effects observed earlier, researchers found that grapes: a) act as an anti-inflammatory agent and b) enhance the activity of a protein complex (20S proteosome) that plays a role in cell cycle regulation including disposal of damaged proteins that contribute to the progression of cancer.

In a follow-up study that utilized both a short-term model of UVB-mediated skin damage and long-term model of skin carcinogenesis, researchers observed that with a grape-enriched diet there was a reduction in tumor growth and malignant conversion of cells, where cells in normal tissue or benign tumors become cancerous. These benefits are attributed to the antioxidant properties of grapes, which likely inhibit early oxidative injury, leading to downstream anti-inflammatory effects and changes in other pathways.

 

17. Oak, A.S.W., Shafi, R., Elsayed, M., Bae, S., Saag, L., Wang, C.L., & Elmets, C.A. (2021). Dietary table grape protects against UV photodamage in humans: 1. clinical evaluation. Journal of the American Academy of Dermatology. doi.org/10.1016/j.jaad.2021.01.035

18. Oak, A.S.W., Shafi, R., Elsayed, M., Mishra, B., Bae, S., Barnes, S., Slominksi, A.T., Wilson, L.S., Athar, M., & Elmets, C.A. (2021). Dietary table grape protects against UV photodamage in humans: 2. molecular evaluation. Journal of the American Academy of Dermatology. doi.org/10.1016/j.jaad.2021.01.036

19. Pezzuto, J.M.; Dave, A.; Park, E.J.; Beyoglu, D.; Idle, J.R. Short-Term Grape Consumption Diminishes UV-Induced Skin Erythema. Antioxidants 2022, 11, 2372. doi.org/10.3390/antiox11122372

20.  Singh, CK., Mintie, CA., Ndiaye, MA., Chhabra, G., Dakup, PP., Ye, T., Yu, M., & Ahmad, N. (2018). Chemoprotective Effects of Dietary Grape Powder on UVB Radiation-Mediated Skin Carcinogenesis in SKH-1 Hairless Mice. Journal of Investigative Dermatology, 1 – 10.  doi.org/10.1016/j.jid.2018.09.028.

21. Mintie, C.A., Singh, C.K., Ndiaye, M.A., Barrett-Wilt, G.A. & Ahmad, N. (2019). Identification of molecular targets of dietary grape-mediated chemoprevention of ultraviolet B skin carcinogenesis: a comparative quantitative proteomics analysis. Journal of Proteome Research. 3741-3751. doi.org.10.1021/acs.jproteome.9b00442.

22. Mintie, C.A., Musarra, A.K., Singh, C.K., Ndiaye, M.A., Sullivan, R., Eickhoff, J.C. & Ahmad, N. (2020). Protective effects of dietary grape on UVB-mediated cutaneous damages and skin tumorigenesis in SKH-1 mice. Cancers. 12, 1751. doi.org/10.3390/cancers12071751.

Grape extract helped to reduce inflammation and insulin resistance mediated by both immune cells and fat cells, and preserved cell function.²³

In a cell study of immune and fat cells, grapes were shown to reduce inflammation and insulin resistance (improved glucose uptake) by fat cells, thus helping to protect important cell functions.  Obesity and type 2 diabetes are both linked to chronic inflammation in fat tissue.

 

A grape-enriched diet improved glucose tolerance and reduced markers of inflammation without affecting body fat levels in obese animals.²⁴

This study looked at the anti-inflammatory properties of grape powder and grape powder extract as well as their impact on glucose tolerance in high-fat-fed obese animals.  The grape powder diet improved glucose tolerance at five weeks but not beyond, and decreased markers of inflammation in both serum and adipose tissue at 18 weeks.  Quercetin showed anti-inflammatory effects on human fat cells. The grape extract had no impact on glucose tolerance at any time point.

A grape-enriched diet reduced baseline steady state levels of inflammatory signaling in the body.²⁵

In this study of inflammation in an animal model, consuming a 4% grape-enriched diet significantly reduced baseline levels of inflammatory signaling (NF-kB activity.)  Although no significant benefit was seen against externally-induced sources of inflammation in both acute and repeated exposures, the baseline levels of inflammatory cytokines (IL-6 and TNF-?) in the animals within the acute challenge group were lower in the grape-fed group versus the control group.  The investigators note that persistent low-grade inflammation is a hallmark of many chronic diseases and that a grape-enriched diet may help suppress this harmful effect.

 

23. Overman, A., Bumrungpert, A., Kennedy, A., Martinez, K., Chuang, C.C., West, T., …McIntosh, M.K. (2010, January).  Polyphenol-rich grape powder extract (GPE) attenuates inflammation in human macrophages and in human adipocytes exposed to macrophage-conditioned media. International Journal of Obesity, 34(5):8000-8.  doi.org/10.1038/ijo.2009.296

24. Chuang, C.C., Shen, W., Chen, H., Xie, G., Jia, W., Chung, S., & McIntosh, M.K. (2012).  Differential effects of grape powder and its extract on glucose tolerance and chronic inflammation in high-fat-fed obese mice.  Journal of Agricultural and Food Chemistry, 60, 12458-12468. doi.org/10.1021/jf3028107

25.  Miller, AS., White, JA., Chowdhury, R., Gales, DN., Tameru, B., Tiwari, AK., & Samuel, T. (2018). Effects of consumption of whole grape powder on basal NF-kB signaling and inflammatory cytokine secretion in a mouse model of inflammation. Journal of Nutrition & Intermediary Metabolism, 11: 1-8.  doi.org/10.1016/j.jnim.2017.11.002

A grape-enriched diet increased bone calcium retention and cortical bone properties in an animal model for menopause.²⁶

In this study, the animals consuming the grape-enriched diet had increased bone calcium retention and cortical bone properties – specifically greater thickness and breaking strength – than those without grapes in their diet.

 

26. Hohman, E.E., & Weaver,M. (2015). A grape-enriched diet increases bone calcium retention and cortical bone properties in ovariectomized rats. Journal of Nutrition, 145(2), 253-9. doi.org/10.3945/jn.114.198598

The role of grapes in maintaining cell health to prevent the development of cancer is an area of ongoing scientific interest, with promising preliminary work in the areas of breast, prostate and colon cancers.²⁷

A grape-enriched diet significantly reduced the expression of cancer-promoting genes in healthy colon tissue.^28,29

In a human study of five colon cancer patients, researchers studied the effects of consuming grapes on colon tissue.  The subjects consumed whole grape powder every day for two weeks; samples of healthy and cancerous colon tissues were taken before and after consuming the grape diet.  The results showed that subjects consuming the equivalent of 2 1/2 cups of grapes for two weeks showed a 47% reduction in the expression of certain target genes involved in the WNT-signaling pathway that are responsible for promoting tumor growth in the colon.  This beneficial effect was seen in the subjects’ healthy colon tissue, but not the cancerous, suggesting that regular consumption of grapes may help to maintain a healthy colon.

In a second study, 30 healthy subjects were randomly assigned to one of three diets: consuming either 1/3, 2/3 or one pound of grapes each day for two weeks.  Samples of colon tissue were taken before and after consuming the grape diets. The results showed that grape consumption at all three levels inhibited the expression of Wnt pathway target genes and markers of mucosal proliferation involved in cancer promotion.  The researchers noted that the potential benefits of grape intake are most significant for high-risk older individuals and individuals whose diet is high in arginine intake; both of these groups have an increased incidence of colon cancer.

A grape-enriched diet helped protect against UVB radiation-mediated skin cancer. ³⁰

In a study using an animal model for UVB-induced skin cancer, consuming either a 3% or 5% grape powder diet for 28 weeks significantly inhibited tumor incidence and delayed the onset of tumor growth.  The grape-mediated protective response was accompanied by enhanced DNA damage repair; reduced proliferation; increased cancer cell death; and beneficial changes in several markers of oxidative stress.

Grape extract demonstrated anti-cancer activity alone, but was more potent in combination with green tea.³¹

In an animal study, tumor growth was stimulated with a specific cancer-growth protein, and the impact of grapes and green tea was tested. Researchers found that a whole grape extract had some effect, but a grape skin extract combined with green tea was more effective.  Green tea on its own provided no impact.

Additionally, cell studies compared the ability of various grape extracts to inhibit the growth protein in human cervical cells and animal mammary cells.  Grapes and green tea combined were more effective than either alone.  Grape skin extracts were more effective than whole grape extract or a grape juice extract.  This study also observed that grape polyphenols (specifically flavonoids) inhibited the growth protein without impacting healthy cells.

 

27. Vislocky, L.M., & Fernandez, M. (2010). Biomedical effects of grape products. Nutrition Reviews. Vol. 68(11), 656-670.  doi.org/10.1111/j.1753-4887.2010.00335.x

28. Nguyen, A.V., Marinez, M., Stamos, M.J., Moyer, M.P., Planutis, K., Hope, C., & Holcombe, R.F. (2009). Results of a phase I pilot clinical trial examining the effect of plant-derived resveratrol and grape powder on Wnt pathway target gene expression in colonic mucosa and colon cancer. Journal of Cancer Management and Research, 1, 25-37. www.ncbi.nlm.nih.gov/pmc/articles/pmc3004662/ 

29. Holcombe, R.F., Martinez, M., Planutis, K., & Planutiene, M. (2015). Effects of a grape-supplemented diet on proliferation and Wnt signaling in the colonic mucosa are greatest for those over 50 and with high arginine consumption.  Nutrition Journal, 14:62. doi.org/10.1186/s12937-015-0050-z

30. Singh, CK., Mintie, CA., Ndiaye, MA., Chhabra, G., Dakup, PP., Ye, T., Yu, M., & Ahmad, N. (2018). Chemoprotective Effects of Dietary Grape Powder on UVB Radiation-Mediated Skin Carcinogenesis in SKH-1 Hairless Mice. Journal of Investigative Dermatology, 1 – 10.  doi.org/10.1016/j.jid.2018.09.028

31. Morré, D.M., & Morré D.J. (2006, July).  Anticancer activity of grape and grape skin extracts alone and combined with green tea infusions. Cancer Letters, 18, 238(2), 202-9.   doi.org/10.1016/j.canlet.2005.07.011

A grape enriched diet helped counter the negative effects of a high fat diet, including fatty liver disease.³²

This study explored the potential of grape consumption to modulate adverse effects caused by a high-fat (western-pattern) diet. Female mice either consumed a standard diet, a grape-enriched diet (5%), a high-fat diet, or a high-fat diet supplemented with 5% grape powder. In the standard group consuming grapes, researchers observed beneficial effects including enriched RNA mitochondria and improved metabolic pathways. In the high-fat diet group, grapes also had a beneficial impact, modulating liver gene expression; preventing oxidative damage; inducing fatty acid metabolism, defending against non-alcoholic fatty liver disease and increasing longevity.

Grape extract helped promote the healthy functioning of liver cells, and protected liver cells from oxidative stress and cell death.³³

Preventing liver cell death (apoptosis) may lead to the prevention of various liver diseases, and cell mitochondria are pivotal in controlling cell life and death.

In this cell study, grape extract helped promote liver cell viability, growth, and metabolic activity.  Specifically, grapes positively influenced a critical cell communication pathway that regulates liver cell health.  Additionally, grapes helped protect the cells against oxidative stress and mitochondrial injury.

 

32. Dave, A.; Park, E.-J.; Kumar,A.; Parande, F.; Beyoglu, D.; Idle, J.R.; Pezzuto, J.M. (2022). Consumption of grapes modulates gene expression, reduces non-alcoholic fatty liver disease, and extends longevity in female C57BL/6J mice provided with a high-fat western-pattern diet. Foods, 11, 1984. doi.org/10.3390/foods11131984

33. Xu, Y., Khaoustov, V.I., Wang, H., Yu, J., Tabassam, F., & Yoffe, B. (2009).  Freeze-dried grape powder attenuates mitochondria- and oxidative stress-mediated apoptosis in liver cells. Journal of Agricultural and Food Chemistry, 57:9324-9331.  doi.org/10.1021/jf900851n

Daily intake of grapes reduced the progression of kidney disease associated with metabolic syndrome.³⁴

In a study using an animal model for metabolic syndrome-associated chronic kidney disease, consuming a 5% grape powder diet for 6 months protected renal function in obese, diabetic animals, preventing the progression of kidney disease.  The grape-enriched diet prevented kidney tissue damage by increasing antioxidant defense in the kidneys – upregulating antioxidant promoting genes and downregulating genes linked to oxidative stress. Consumption of the grape diet also lowered serum glucose and improved serum protein status.

 

34.  Almomen, SMK., Guan, Q., Liang, P., Yang, K., Sidiqi, AM., Levin, A., & Du, C. (2017). Daily Intake of Grape Powder Prevents the Progression of Kidney Disease in Obese Type 2 Diabetic ZSF1 Rats. Nutrients, 9, 345. doi.org/10.3390/nu9040345

Grape consumption helped reduce the onset of autoimmune diabetes in animals.³⁵

In this study, a grape-enriched diet protected against the destruction of insulin-producing cells in the pancreas, reduced levels of inflammation in the spleen, and increased antioxidant capacity in non-obese, diabetic animals.

 

35. Zunino, S.J., Storms, D.H., & Stephensen, C.B. (2007).  Diets rich in polyphenols and vitamin A inhibit the development of Type 1 autoimmune diabetes in nonobese diabetic mice. Journal of Nutrition,  137, 1216-1221. doi.org/10.1093/jn/137.5.1216

A grape-enriched diet helped protect bladder function against oxidative damage caused by obstruction to the bladder. ^{36, 37, 38}

Obstructive bladder dysfunction, such as that observed with prostate enlargement, is linked to oxidative damage of the nerves, synapses, and smooth muscle cells within the bladder wall.  A series of animal studies investigated the impact of adding grapes to the diet on bladder function.  The studies showed that grapes provided an antioxidant effect that helped to prevent and delay the damaging effects of oxygen deprivation (ischemia) and free radicals to cells that result from a partial obstruction to the bladder.  Grapes helped maintain membrane and mitochondrial function in the cells, and helped reduce and reverse bladder damage caused by a partial outlet obstruction.  The beneficial effects were attributed to the combination of multiple active components in grapes — not just one.

 

36. Agartan, C.A., Whitbeck, C., Sokol, R., Chichester, P., & Levin, R.M. (2004). Protection of urinary bladder function by grape suspension. Phytotherapy Research, 18, 1013-18. doi.org/10.1002/ptr.1620

37. Lin, A.Y., Mannikarottu, A., Chaudhry, A., Whitbeck, C., Kogan, B.A., Chichester, P., & Levin, R.M. (2005, December). Protective effects of grape suspension on in vivo ischemia/reperfusion of the rabbit bladder. British Journal of Urology International, 96, 1397-402. doi.org/10.1111/j.1464-410x.2005.05832.x

38. Venugopal, V., Leggett, R.E., Shuler, C., & Levin, R.M. (2010, November-December). Effect of hydrogen peroxide on rabbit urinary bladder citrate synthase activity in the presence and absence of a grape suspension. International Brazilian Journal of Urology, 36(6):749–758. doi.org/10.1590/s1677-55382010000600014